Single cell bypass panels

[TeddyDiver]

Hello everyone!
On a sailboat there's limited space and some shading over one part of the solar panels so I wish to maximize the output of the panels. What I have in mind is to have bypass diodes in every individual cell so partial shading would cause as little power loss as possible. Anyone done this or if there are any commercial products setup this way? If DIY is the only way to go I'm thinking about having each cell framed individually which makes the glazing lighter and easy to swap a replacement incase of malfunction in one cell. I'd like to arrange all cells in series to a single MPPT.

BR Teddy

[inetdog]

Well, one problem with that design is that the bypass diodes cost money, in some cases quite a lot of money.
Second problem is that depending on the type of diode and current involved compared to the maximum current rating of the diode you will have a forward voltage drop ranging from .2V to as much as 1.0V across each diode.
Bypassing a group of cells that together contribute 10V (that is about 20 cells) using one diode per cell will result in a voltage drop ranging from 4 volts to 20 volts. You would, in many cases, be better off just dropping the whole panel out of the string using a single bypass diode around the whole panel.
The standard design of commercial panels, with two to four bypass groups, is a balance of component cost, assembly complexity and power lost due to shading.
If you know in advance exactly how a panel will be shaded you may find a better diode arrangement for that particular panel in that particular installation, but nobody would make that to order for you.

Framing each cell individually makes more sense at first glance, but the economics (and weight) of actually encapsulating each cell individually with its own wire leads is likely to make it impractical.
Any DIY panel is not going to last long in the environment of a sailboat.

[SunEagle]

Well, one problem with that design is that the bypass diodes cost money, in some cases quite a lot of money.
Second problem is that depending on the type of diode and current involved compared to the maximum current rating of the diode you will have a forward voltage drop ranging from .2V to as much as 1.0V across each diode.
Bypassing a group of cells that together contribute 10V (that is about 20 cells) using one diode per cell will result in a voltage drop ranging from 4 volts to 20 volts. You would, in many cases, be better off just dropping the whole panel out of the string using a single bypass diode around the whole panel.
The standard design of commercial panels, with two to four bypass groups, is a balance of component cost, assembly complexity and power lost due to shading.
If you know in advance exactly how a panel will be shaded you may find a better diode arrangement for that particular panel in that particular installation, but nobody would make that to order for you.

Framing each cell individually makes more sense at first glance, but the economics (and weight) of actually encapsulating each cell individually with its own wire leads is likely to make it impractical.
Any DIY panel is not going to last long in the environment of a sailboat.

But think of the possibilities of having individual pv cells that you can configure like a puzzle into any configuration you want that can act separately or as a group using a meshed network grid to generate different voltages and amp outputs.

Costly... YES, but could be very useful for out of the ordinary surfaces and loads.

[PNjunction]

What I have in mind is to have bypass diodes in every individual cell so partial shading would cause as little power loss as possible. Anyone done this or if there are any commercial products setup this way? If DIY is the only way to go I'm thinking about having each cell framed individually which makes the glazing lighter and easy to swap a replacement incase of malfunction in one cell. I'd like to arrange all cells in series to a single MPPT.

Looks like you are headed in the direction of active-diodes / integrated diodes which have better performance than even Schottky. A quick intro from DigiKey about them:

https://www.digikey.com/en/articles/techzone/2012/dec/active-bypass-diodes-improve-solar-panel-efficiency-and-performance

I'm not sure the smaller "integrated" ones are even available yet. TI's spec sheet for the SM74611:

http://www.ti.com/product/SM74611

Might be fun to play with for a diy proof-of-concept.

In the real world, if these play out at a reasonable cost, one would have to watch out for too-good-to-be-true counterfeits, and pure scams substituting ordinary diodes instead.